Pain in the Webbing Between Thumb and Index Finger

Pain in the webbing between the thumb and index finger, also called discomfort in the first dorsal web space, is not a common hand complaint. Patients may notice aching, tightness, or pressure in the fleshy area between the thumb and index metacarpal. 

When conditions such as rheumatoid arthritis, nerve compression, or nerve entrapment are excluded, the discomfort may be linked to muscle overuse or elevated pressure within this small muscle compartment.

Other common forms of hand pain, including wrist pain or pain in the middle finger or ring finger, typically present with different symptoms and causes. This distinction highlights the importance of accurate diagnosis for pain located specifically between the thumb and index finger.

Understanding Pain in the Webbing Between Thumb and Index Finger

Pain in the webbing between the thumb and index finger can be frustrating and difficult to pinpoint. On the thumb side of the hand, patients may describe aching, pressure, or weakness in the first dorsal web space. While not as common as symptoms of carpal tunnel syndrome or thumb arthritis, this discomfort may interfere with everyday activities like gripping, pinching, or writing. 

Because the causes range from simple overuse to rare conditions like dynamic first dorsal interosseous compartment syndrome, an accurate diagnosis is essential to ensure proper treatment and lasting relief.

Diagnosis of First Dorsal Web Space Pain

Diagnosing pain in the webbing between the thumb and index finger requires careful evaluation. One method is intracompartmental pressure measurement, which is also used for other types of compartment syndrome. This test can be performed with a wick catheter or a Stryker device to measure pressure levels inside the dorsal web space of the first dorsal interosseous muscle compartment.

In addition, Dr. A. Lee Dellon described a stress test in which a patient repeatedly performs a key pinch (pressing the thumb and index finger together). If the strength weakens and pain develops in the web space during this repetitive motion, it may suggest dynamic first dorsal interosseous compartment syndrome.

In some cases, additional studies may be considered to rule out nerve-related conditions. For example, nerve conduction testing can help identify issues with the median nerve or other nerves if nerve compression is suspected as a source of web space pain.

Treatment of Pain Between Thumb and Index Finger

Treatment depends on the underlying cause of the pain in the webbing between the thumb and index finger. In the few published cases of dynamic first dorsal interosseous compartment syndrome, surgical decompression relieved the pressure within the muscle compartment. After surgery, patients regained pinch strength and experienced resolution of their web space pain.

Before surgical options are considered, conservative care may be recommended. This can include activity modification, rest, and nonsteroidal anti-inflammatory medications to reduce inflammation and relieve discomfort. Treatment is tailored depending on whether the problem arises from muscle pressure, nerve entrapment, or joint conditions such as rheumatoid arthritis.

Although this condition is rare, it is important for physicians to keep an open mind and consider it as part of the differential diagnosis when more common conditions, such as arthritis or ulnar nerve entrapment, have been excluded.

When to Seek Medical Care

Occasional mild discomfort between the thumb and index finger may improve with rest, ice, and activity modification. However, patients should seek medical evaluation if they notice:

• Persistent or worsening hand pain in the webbing area
• Numbness and tingling in the thumb, index finger, or side of the wrist
• Weakness when pinching or gripping objects
• Pain involving other areas, such as the wrist, ring finger, or middle finger
• Pain that does not improve with conservative care

Early diagnosis is important, as timely treatment may prevent further weakness or loss of function in the hand.